The agent was an aeronautical engineer recruited in 1967, say papers smuggled out of Russia by dissident KGB officer Vasili Mitrokhin.

Ace handed over documents spanning more than 90,000 pages of detailed technical specifications on new aircraft including Concorde, the Super VC-10 and Lockheed L-1011.

Concordski: Spot the difference

And his details on flight simulators "were the foundation of a new generation of Soviet equivalents", according to the book The Mitrokhin Archive, based on the papers.

Russia's ill-fated Tupolev TV-144, dubbed Concordski, was strikingly similar to Concorde.

One of the most highly valued of the agents working in Britain during the 1970s, Ace, whose real identity is not revealed, was paid �225 a month for his efforts, a figure that rose to �350 just before he died in the early 1980s.

The agent was just one of more than a dozen spies operating within Britain and passing commercial and technological secrets to the Russians at the height of the Cold War, the papers reveal.

Vasili Mitrokhin: More revelations

They included chemists, a nuclear physicist, a virologist, aeronautical engineers and a laboratory assistant.

The details are revealed in papers smuggled out by Mitrokhin, which also revealed the identity of great grandmother Melita Norwood who passed vital information about the British atom bomb to the Soviets.

Former police officer John Symonds has also admitted being a "Romeo agent" who tried to get secrets for the KGB by sleeping with women from foreign embassies in the 1970s.

Two former Labour MPs, Tom Driberg and Raymond Fletcher, who are both now dead, were also listed as KGB agents.